Morpho-biochemical characterization and molecular diversity analysis of bael [Aegle marmelos (L.) Correa.] germplasm using gene-targeted molecular markers
Arvind Kumar Singh, Chet Ram, Ramkesh Meena, Lalu Prasad Yadav, Gangadhara Kaldappa, J. Góra, Mukesh Kumar Berwal, Jagadish Rane
Abstract
• The first comprehensive report of gene-based markers employment in bael crop. • CBDT markers has identified as the most robust marker than SCoT in bael. • CBDP9, CBDP18, SCoT22, SCoT23, and SCoT25 exhibited high levels of polymorphism and marker efficiency. • A highly significant correlation obtained between morpho-biochemical traits and genotypes during principal component analysis. • Based on morphological traits, two hierarchical clusters obtained. The bael fruit [ Aegle marmelos (L.) Correa.] is a native crop of the Indian subcontinent with remarkable medicinal value, yet its potential remains largely untapped. The genetic diversity of bael germplasm has been conserved with substantial amounts in gene banks across the Indian continent. However, characterization studies utilizing morpho-biochemical and gene-targeted [Start Codon Targeted Polymorphism (SCoT) and CAAT Box-Derived Polymorphism (CBDP)] molecular markers analysis are scanty in bael germplasm. Therefore, the study was aimed to assess the genetic diversity based on leaf and fruit characters, and establish phylogenetic relationships among 19 bael genotypes using gene-targeted markers. Two marker systems viz., 9 CBDP and 18 SCoT markers were employed in this study, which collectively produced 32 and 88 bands, with an average of 3.56 and 4.89 bands per primer, respectively. Notably, CBDP9 and CBDP18 exhibited the highest number of polymorphic bands, while SCoT22, SCoT23 and SCoT25 demonstrated high levels of polymorphism and marker efficiency. Both marker systems (CBDP and SCoT) yielded significant and moderate levels of Polymorphic Information Content (PIC) values, ranging from 0.23 to 0.52 and 0.11 to 0.47, respectively among the tested bael genotypes. Moreover, marker efficiency analysis identified CBDP markers as robust compared to SCoT markers in this study. Combining data from both marker systems supported to cluster the 19 bael genotypes into two major groups, with further dividing of the major group I into four sub-groups (Ia, Ib, Ic, and Id). Remarkably, the cultivar Pant Urvashi was identified as an outlier, clustered separately in group II in the phylogenetic tree. Additionally, molecular analysis revealed four major population structures among the 19 bael genotypes. Likewise, the AMOVA results revealed a large genetic variation within populations rather than among the populations. Furthermore, Principal Component Analysis (PCA) highlighted significant correlations between quantitative traits (leaf and fruit traits) and genotypes. Agglomerative hierarchical clustering analysis based on leaf morphological parameters also identified two major clusters among the bael genotypes. The information regarding genetic diversity and robust markers obtained in this study hold promise for molecular breeding programs aimed to improve bael fruit crops in future.